CHAPTER XIX. 147 one cause be sufficient to produce the effect, or whether it does not require a concurrenceof several causes ; and then endeavour as far as possible, to adjust the degrees of influence that each cause might have in producing the effect, and the proper agency and influence of each of them therein. . So in natural philosophy, if I would find what are theprin- ciples or causes of that sensation which we call heat when I stand near the fire ; here I shall find it is necessary that there be an agency of the particles of fire on my flesh, either mediately by themselves, or at least by the intermediate air ; there must be a particular sort of motion and vellication imprest upon my nerves ; there must be a derivation of that motion to the brain ; and there must be an attention of my soul to this motion ; if either of these are wanting, the sensation of heat will not be produced. So in the moral world, if I enquire into the revolution of a state or kingdom, perhaps I find it brought about by the tyranny or folly of a prince, or by the disaffection of his own subjects ; and this disaffection and opposition may arise, either upon the account of impositions in religion, or injuries relating to their civil rights ; or the revolution may be effected by the invasion of a foreign army, or by the opposition of some person at home or abroad that lays claim to the government, &c. or a hero who would guard the liberties of the people ; or by many of these concurring together ; then we must adjust the influences of each as wisely as we can, and not ascribe the whole event to one of them alone. II. When we are enquiring into the effects of any particular cause or causes, we may follow this method 1. Consider diligently the nature of every cause apart, and observe what effect every part or property of it will tend to .pro- duce.-2. Consider the causes united together in their several natures, and.ways of operation ; enquire how far the powers or properties of one, will hinder or promote the effects of the other, and wisely balance the proportions of the influence. -3. Consider what the subject is, in or upon which the cause is to operate ; for the same cause on different subjects will oftentimes produce dif- ferent effects, as the sun which softens wax will harden clay. 4. Be frequent and diligent in making all proper experiments; in setting such causes at work whose effects you desire to know, and putting together in an orderly manner, such things as arc most likely to produce some useful effects, according to the best survey you can take of all the concurring cases and circumstan- ces.-5. Observe carefully all the events which happen either by an occasional concurrence of various causes, or by the industrious application of knowing men ; and when you see any happy effect certainly produced, and often repeated, treasure it up together x2
RkJQdWJsaXNoZXIy OTcyMjk=